一 android automative架构
car app:
packages/services/Car/car_product/build/car.mk 这个文件中列出了汽车系统中专有的模块：
BOARD_PLAT_PUBLIC_SEPOLICY_DIR += packages/services/Car/car_product/sepolicy/public
BOARD_PLAT_PRIVATE_SEPOLICY_DIR += packages/services/Car/car_product/sepolicy/private
# Automotive specific packages
PRODUCT_PACKAGES +=
CarService
CarTrustAgentService
CarDialerApp
CarRadioApp
OverviewApp
CarLauncher
CarLensPickerApp
LocalMediaPlayer
CarMediaApp
CarMessengerApp
CarHvacApp
CarMapsPlaceholder
CarLatinIME
CarSettings
CarUsbHandler
android.car
car-frameworks-service
com.android.car.procfsinspector
libcar-framework-service-jni
# System Server components
PRODUCT_SYSTEM_SERVER_JARS += car-frameworks-service
# should add to BOOT_JARS only once
ifeq (,$(INCLUDED_ANDROID_CAR_TO_PRODUCT_BOOT_JARS))
PRODUCT_BOOT_JARS +=
android.car
INCLUDED_ANDROID_CAR_TO_PRODUCT_BOOT_JARS := yes
endif
car api:
packages/services/Car/car-lib/
android.car：包含了与车相关的基本API。例如：车辆后视镜，门，座位，窗口等。
annotation：包含了两个注解。
app
menu：车辆应用菜单相关API。
cluster：仪表盘相关API。
render：渲染相关API。
content
pm：应用包相关API。
diagnostic：包含与汽车诊断相关的API。
hardware：车辆硬件相关API。
cabin：座舱相关API。
hvac：通风空调相关API。（hvac是Heating, ventilation and air conditioning的缩写）
property：属性相关API。
radio：收音机相关API。
input：输入相关API。
media：多媒体相关API。
navigation：导航相关API。
settings：设置相关API。
vms：汽车监测相关API
car service:
Car Service并非一个服务，而是一系列的服务这些服务都在ICarImpl.java构造函数中列了出来。
public ICarImpl(Context serviceContext, IVehicle vehicle, SystemInterface systemInterface,
CanBusErrorNotifier errorNotifier, String vehicleInterfaceName) {
mContext = serviceContext;
mSystemInterface = systemInterface;
mHal = new VehicleHal(vehicle);
mVehicleInterfaceName = vehicleInterfaceName;
mSystemActivityMonitoringService = new SystemActivityMonitoringService(serviceContext);
mCarPowerManagementService = new CarPowerManagementService(mContext, mHal.getPowerHal(),
systemInterface);
mCarPropertyService = new CarPropertyService(serviceContext, mHal.getPropertyHal());
mCarDrivingStateService = new CarDrivingStateService(serviceContext, mCarPropertyService);
mCarUXRestrictionsService = new CarUxRestrictionsManagerService(serviceContext,
mCarDrivingStateService, mCarPropertyService);
mCarPackageManagerService = new CarPackageManagerService(serviceContext,
mCarUXRestrictionsService,
mSystemActivityMonitoringService);
mCarInputService = new CarInputService(serviceContext, mHal.getInputHal());
mCarProjectionService = new CarProjectionService(serviceContext, mCarInputService);
mGarageModeService = new GarageModeService(mContext, mCarPowerManagementService);
mCarLocationService = new CarLocationService(mContext, mCarPowerManagementService,
mCarPropertyService);
mAppFocusService = new AppFocusService(serviceContext, mSystemActivityMonitoringService);
mCarAudioService = new CarAudioService(serviceContext);
mCarNightService = new CarNightService(serviceContext, mCarPropertyService);
mInstrumentClusterService = new InstrumentClusterService(serviceContext,
mAppFocusService, mCarInputService);
mSystemStateControllerService = new SystemStateControllerService(serviceContext,
mCarPowerManagementService, mCarAudioService, this);
mPerUserCarServiceHelper = new PerUserCarServiceHelper(serviceContext);
mCarBluetoothService = new CarBluetoothService(serviceContext, mCarPropertyService,
mPerUserCarServiceHelper, mCarUXRestrictionsService);
mVmsSubscriberService = new VmsSubscriberService(serviceContext, mHal.getVmsHal());
mVmsPublisherService = new VmsPublisherService(serviceContext, mHal.getVmsHal());
mCarDiagnosticService = new CarDiagnosticService(serviceContext, mHal.getDiagnosticHal());
mCarStorageMonitoringService = new CarStorageMonitoringService(serviceContext,
systemInterface);
mCarConfigurationService =
new CarConfigurationService(serviceContext, new JsonReaderImpl());
mUserManagerHelper = new CarUserManagerHelper(serviceContext);
二 callserive启动流程
1 frameworks/base/services/java/com/android/server/SystemServer.java启动CarServiceHelperService，如下：
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_AUTOMOTIVE)) {
traceBeginAndSlog("StartCarServiceHelperService");
mSystemServiceManager.startService(CarServiceHelperService.class);
traceEnd();
}
而CarServiceHelperService.onStart()会bind到CarService，如下：
Intent intent = new Intent();
intent.setPackage("com.android.car");
intent.setAction(CAR_SERVICE_INTERFACE);
if (!getContext().bindServiceAsUser(intent, mCarServiceConnection, Context.BIND_AUTO_CREATE,
UserHandle.SYSTEM)) {
Slog.wtf(TAG, "cannot start car service");
}
注意：这里用的是bindService方式，mCarServiceConnection是ServiceConnection类对象，它能监听目标Service的状态，当目标Service所在进程异常退出时，会导致其onServiceDisconnected()方法被调用
2 CarService启动其他service
CarService.onCreate()里会创建ICarImpl的实例，并调用ICarImpl.init()方法；
Log.i(CarLog.TAG_SERVICE, "Service onCreate");
mCanBusErrorNotifier = new CanBusErrorNotifier(this );
mVehicle = getVehicle();
if (mVehicle == null) {
throw new IllegalStateException("Vehicle HAL service is not available.");
}
try {
mVehicleInterfaceName = mVehicle.interfaceDescriptor();
} catch (RemoteException e) {
throw new IllegalStateException("Unable to get Vehicle HAL interface descriptor", e);
}
Log.i(CarLog.TAG_SERVICE, "Connected to " + mVehicleInterfaceName);
mICarImpl = new ICarImpl(this, mVehicle, SystemInterface.getDefault(this),
mCanBusErrorNotifier);
mICarImpl.init();
SystemProperties.set("boot.car_service_created", "1");
linkToDeath(mVehicle, mVehicleDeathRecipient);
super.onCreate();
而ICarImpl.init()里会启动一大堆Service，其中就包括InstrumentClusterService，如下
// Be careful with order. Service depending on other service should be inited later.
List allServices = new ArrayList<>(Arrays.asList(
mSystemActivityMonitoringService,
mCarPowerManagementService,
mCarSensorService,
mCarPackageManagerService,
mCarInputService,
mGarageModeService,
mCarInfoService,
mAppFocusService,
mCarAudioService,
mCarCabinService,
mCarHvacService,
mCarRadioService,
mCarNightService,
mInstrumentClusterService,
mCarProjectionService,
mSystemStateControllerService,
mCarVendorExtensionService,
mCarBluetoothService,
mCarDiagnosticService,
mPerUserCarServiceHelper
));
注意服务启动顺序，依赖于其他服务的service靠后初始化。
三 架构图
参考文章：
Android Automotive（三）——CarAudioService（AndroidP）_tudouhuashengmi的博客-CSDN博客
Android CarService 源码分析 - 简书
